Traditional high-intensity luminaires (also popularly termed “fixtures”) for installation in various indoor, outdoor and indoor/outdoor (e.g. parking areas) environments are weatherproof, having durable sealed lens covers that keep moisture, vapor and other contaminants away from their internal lamps, wiring and electrical components. Such luminaires are commonly termed “vapor-tight” fixtures/luminaires. These luminaires generally include a fluorescent lamp assembly within their housing. Currently available designs define a “clamshell” consisting of an elongated, opaque, upper box (typically of polymer material), having pendant mounting brackets, attached electronics (ballast, etc.), wiring, reflector assembly and a plurality of fluorescent lamps in a predetermined number and arrangement; a translucent lower lens having a top edge that mates with the bottom edge of the upper box; and a horizontally oriented and elongated sealing surface created by the upper housing and lower lens mating surfaces. This interface between the upper and lower portions of the luminaire incorporates an elastomeric-type gasket that creates a moisture and dust-resistant seal when a set of housing affixed sealing clamps are employed to compressibly join the housing and lens portions of the luminaire. However, the seal is subject to the effects of aging, and eventually fails over time. This is partially the result of the spacing between sealing clamps and the elongated nature of the horizontal sealing surface (which provides an uneven compression to the joint line) combined with aging of the materials, environmental changes and extremes in temperature. As the seal degrades it allows for the undesirable infiltration of moisture and contaminants. Because the seal is elongated and horizontal, it encourages the buildup and retention of moisture at the seal interface around the perimeter. The moisture seeks a lower level, which it achieves by migrating through any gaps in the seal around the relatively large and intermittently clamped perimeter. Once the moisture enters, it pools in the lens, causing fogging, staining of the lens and eventual failure of the wiring and electronics.
Shortened lamp and electronics (ballast, etc.) life due to moisture-based deterioration increases the costs of maintaining the luminaires, and shortened unit life leads to more frequent replacements and higher costs for the facility owner/operator.
A vapor-tight luminaire with an advanced and efficient reflector and lamp arrangement is provided in commonly assigned U.S. Pat. No. 7,588,347, entitled LIGHTING FIXTURE, by Richard D. Edwards, Jr., which is incorpotrated herein by reference as useful background information. This design provides superior optimetrics with two or three flourescent lamps. However, it relies upon existing vapor-tight housing technology as described generally above. This arrangement makes it difficult to access and service the electronics, as they are generally placed beneath the lamp assembly, requiring removal of a significant portion of the internal components to replace a ballast or other electronic element of the luminaire. Even where servicibility is a secondary concern, the placment of both the electronics and the lamp assembly in a single overall, sealed enclosure can prove problematic where certain types of lamps (e.g. LEDs or incandescent) or electronics generate sognificant heat, and that heat is essentially trapped within the sealed housing, degrading the internal components and potentially degrading the seal through heat damage.
It is, thus, highly desirable to provide a luminaire that uses fluorescent tubular lamps, or another type of elongated light source, which is vapor tight and reduces the deleterious effects on the housing and electronics brought upon by environmental conditions, among other factors. In particular, this luminaire should employ a housing arrangement that avoids the disadvantages of an elongated, horizontal intermittently clamped seal that is prone to accumulate moisture and allow it to migrate through a gap. This luminaire should be able to employ an advanced and efficient lamp arrangement and reflector design, and afford superior photometrics. This luminaire should be easily retrofit into existing structures in a variety of mounting arrangements, such as direct-to-ceiling, pendant, etc. Moreover, the underlying housing structure should allow for straightforward mounting of up-to-date lamp technologies, such as LED, plasma discharge, etc.